Leading seeds Novak Djokovic and Roger Federer made straight-sets progress to the quarter-finals of the Dubai Tennis Championships.

World number one Djokovic downed battling world number 55 Roberto Bautista-Agut in two contrasting sets after Federer broke once in each set to beat another Spanish player, Marcel Granollers.

Djokovic was untroubled in the first set, breaking twice before Bautista-Agut got a game on the board and ultimately winning 6-1.

He broke again at the first time of asking in the second set and held for a 3-0 lead but serving for the match at 5-3, he fell 0-40 behind and Bautista-Agut took his third break point to prolong the match.

The underdog saved three match points during a staggering 16-minute service game at 4-5 before finally levelling the set at 5-5.

It continued to a tie-break and Djokovic led 5-2 before dropping a pair of points on his serve - but then responded with two returning points to complete a 6-1 7-6 (7/4) win in 90 minutes.

In the previous match on court, Federer prevailed 6-3 6-4 against the world number 34.

Federer broke to love to lead 4-2 in the first set and though Granollers produced an outrageous wristy, inside-out forehand down the line, hopelessly wrong-footing the 17-times grand slam champion, to go 30-30 on Federer's serve, the world number two nonetheless closed it out to leave his opponent serving to stay in the set.

The Spaniard held after being pegged back from 40-0 to deuce but Federer held to love to clinch the set in 27 minutes.

Federer broke at the third attempt to lead 3-2 in the second set, having set up the first break point by winning the most spectacular rally in the match. After reaching a drop-shot right at the net, the Swiss countered a point-blank volley with a parry to the baseline which Granollers was unable to chase down.

Granollers saved a match point while serving at 3-5 but Federer served out the match to win in an hour and 11 minutes.

Former world number three Nikolay Davydenko awaits in the next round after the Russian, now ranked 46, beat Romania's Viktor Hanescu 6-4 7-6 (7/2).

Having won the first set, Del Potro broke in the first game of the second and closed out the match with little fuss.

German qualifier Daniel Brands produced an upset with a 6-4 6-4 win over eighth seed Mikhail Youzhny, setting up a clash with Del Potro, but compatriot Tobias Kamke was unable to match that effort against Tomas Berdych.

Berdych saved 12 of 14 break points in a hard-fought first set and raged at the chair umpire after being warned for taking too long between points, under the ATP tour's new 25-second rule, but the third seed still prevailed 7-5 6-1.